Shear Shock Wave Focusing in Human Skull Phantom: Observations with High-Frame Rate Ultrasound Imaging and Matched Simulations

Abstract

We have recently observed that smooth low acceleration shear waves develop into destructive high acceleration shear shocks as they propagate in fresh ex vivo porcine brain. We hypothesize that local amplification of acceleration at the shock front can damage neurons and be responsible for a wide range of traumatic brain injuries. Currently there are no simulation tools for modeling the propagation of shear shock waves in human head. Here, 1) a new system of equations is presented to model the propagation of linearly-polarized shear shock waves in isotropic solids, 2) a generalized Maxwell body is used to model the attenuation/dispersion in soft solids, described by a power law with non-integral exponents, and 3) the resulting system is numerically simulated using a custom high-order finite volume method: piecewise parabolic method. A simulation of shear waves in human skull with brain parameters is shown, along results from on-going experiments of shear wave propagation in gelatin using the same geometry.